The decision to ration NHS use of the anti-impotence drug Viagra could have profound implications for the future of free health care in the UK, says BBC Health Correspondent Richard Hannaford.

The decision by Frank Dobson to limit the use of Viagra represents a major development in the debate over health service rationing. For the first time a Secretary of State has decided to limit the extent to which a drug can be prescribed to NHS patients on purely cost grounds.

Previous decisions to ration medicines, like Beta Interferon for those suffering from multiple sclerosis, have been justified on the grounds that the drugs do not help everyone, and that further research is necessary to discover what sort of patient would, in fact, benefit.

GPs are free to prescribe Viagra to patients on a private basis. The shift to private prescriptions is far more radical than it at first seems.

It implies an acceptance by the government that some GPs will diagnose NHS patients as needing this drug - but will only be able to prescribe it to them if they can pay.

Break with tradition

This could be said to represent a break with the long held health service principle that people are treated on the basis of need, and not on their ability to pay. But it could go even further.

If GPs can see patients under the NHS scheme and prescribe Viagra privately, why shouldn't other doctors do the same for people suffering from other conditions. For example, women with ovarian cancer wanting the drug Taxol - which some health authorities currently restrict - or carers of Alzheimer's patients wanting the drug Aricept.

Consultation on these proposals will end in mid-March. Clearly if no agreement can be reached by then, the GPs and the government could find themselves involved in a serious confrontation. One that in fact neither side wants.